13.2 Guide to Porting Code from Release 3

Release 4 does not provide a mode in which it is 100% compatible with earlier releases. However, in addition to what is said in What Is New In Release 4 (read that first!), this section provides further guidelines for migrating Prolog code from release 3 to release 4.

1. First of all, make sure that your code runs in ISO execution mode. In release 3, the command line option --iso can be used.
2. A number of built-in predicates have been dropped. They are listed in the table below, along with their approximate substitutes. Refer to the documentation for each case.

   Dropped built-in	Replaced by
   get0/[1,2], get/[1,2]	get_code/[1,2], get_byte/[1,2]
   ttyget0/1, ttyget/1	get_code/2, get_byte/2
   put/[1,2], tab/[1,2]	put_code/[1,2], put_byte/[1,2]
   ttyput/1, ttytab/1	put_code/2, put_byte/2
   skip/[1,2]	skip_code/[1,2], skip_byte/[1,2]
   ttyskip/1	skip_code/2, skip_byte/2
   ttynl/0	nl/1
   ttyflush/0	flush_output/1
   fileerrors/0, nofileerrors/0	set_prolog_flag/2
   'C'/3	unification
   call_residue/2	call_residue_vars/2
   undo/1	prolog:undo/1
   help/0	the message system
   version/0	the message system
   version/1	the message system
   fcompile/1	save_files/2
   load/1	load_files/2
   load_foreign_files/2	splfr + load_foreign_resource/1
   require/1	use_module/2
   is_mutable/1	mutable/1
   module/1	set_module/1

3. The hook predicates user:term_expansion/[2,4] and user:term_expansion/3 are now called user:term_expansion/6 and Module:term_expansion/5 and have a modified API; see Term and Goal Expansion.
4. The set of library modules has been enriched by incorporating a subset of the Quintus Prolog library modules that we have deemed useful.

   library(clpb), library(clpq) and library(clpr) are provided but not supported. library(flinkage) and library(spaceout) are not included in release 4. library(objects) has been replaced by its Quintus counterpart, with a completely different API.

   The following table lists the affected SICStus 3 library modules.

   Affected module	Closest equivalent	Comment
   arrays	arrays3	a
   assoc	assoc3	b
   charsio	codesio	c
   clpfd	clpfd	d
   lists	lists3	e
   queues	queues3	f
   random	random3	g
   sockets	sockets	d
   system	system3	h
   terms	terms	d

   Comments to the table:

   1. library(arrays3) is a code migration library module; the long-term solution is to use library(logarrs) instead.
   2. library(assoc3) is a code migration library module; the long-term solution is to use library(avl) instead.
   3. The syllable ‘chars’ has been changed to ‘codes’ throughout.
   4. Several API changes; see the documentation.
   5. library(lists3) is a code migration library module; the long-term solution is to use library(lists) instead.
   6. library(queues3) is a code migration library module; the long-term solution is to use library(queues) instead.
   7. library(random3) is a code migration library module; the long-term solution is to use library(random) instead.
   8. library(system3) is a code migration library module; the long-term solution is to use library(system), library(file_systems) and library(process) instead.

      One difference between library(system3) and the original release 3 version is that exec/3 returns a process reference, a compound term, instead of an integer process identifier.